There are three major causes that lead to low platelet counts. The condition may be caused if the bone marrow does not produce enough platelets, there is an increased breakdown of platelets in the bloodstream (intravascular) or there is an increased breakdown of platelets in the spleen (extravascular).
Insufficient platelets produced: Several disorders, including aplastic anemia and bone marrow cancer may affect the bone marrow's ability to produce platelets. In rare cases, bone marrow infections or certain drugs (such as chemotherapy) may also inhibit the bone marrow from producing enough of the cells.
Increased platelets destroyed in bloodstream: There are also many disorders that lead to the destruction of platelets in the body. Examples include: Gram-negative sepsis, acute promyelocytic leukemia, anemia, malaria, tuberculosis or various connective tissue and inflammatory diseases. Certain medications, such as heparin, quinidine, quinine, sulfa-containing antibiotics, some oral hypoglycemia agents (drugs that treat diabetes) like diazoxide, gold salts and rifampin, may also destroy platelets. The drugs may destroy platelets directly or they may initiate an autoimmune response, causing the body to produce antibodies against platelets. Pregnancy may also cause mild thrombocytopenia.
Increased platelets destroyed in the spleen: Individuals who have an enlarged spleen are at risk for developing thrombocytopenia. In healthy individuals, the spleen works to fight infection and filters unwanted material from the blood. Normally, about one-third of the body's platelets are located in the spleen while the rest circulate in the blood. However, when the spleen becomes enlarged (which can be the result of many different disorders), the spleen may harbor too many platelets, which causes a decrease in the number of platelets in circulation.
Symptoms of thrombocytopenia can range from mild to severe. Individuals with mild cases may be asymptomatic. The duration and severity of symptoms depends on the cause. For instance, ITP is often a chronic condition that may last for years, while most drug-induced thrombocytopenic patients recover within seven to ten days after they stop taking the medication.
Symptoms of thrombocytopenia often include nosebleeds, bleeding in the mouth, easy or excessive bruising, prolonged bleeding from cuts, blood in stools, blood in urine, blood in vomit, purpura (purplish discolorations in the skin produced by small bleeding vessels near the surface of the skin), unusually heavy menstrual flows, profuse bleeding during surgery and superficial bleeding into the skin (that looks like a rash).
TTP may also cause fever, weakness, fatigue, pallor (pale skin), shortness of breath, increased heartbeat, bleeding into the skin or mucus membranes, confusion, speech changes, alterations in consciousness, jaundice (yellowing of the skin and eyes) and kidney failure.
Mild thrombocytopenia often causes no signs or symptoms. A routine blood test may detect a low platelet count even if symptoms are not present. A fibrinogen test may also detect low levels of platelets. Once thrombocytopenia has been diagnosed, a bone marrow biopsy can be performed to determine whether the bone marrow is producing a sufficient number of platelets. Individuals who are at risk of developing thrombocytopenia (like pregnant women) should consult a qualified healthcare physician who can monitor their platelet count regularly.
CBC: A complete blood count (CBC) is usually conducted to determine how many and what types of cells are in the blood. This blood test can detect a low platelet count.
Bone marrow biopsy: A bone marrow biopsy may be performed to confirm a diagnosis. During the biopsy, the patient is given a local anesthetic, and a sample of bone marrow is removed with a needle. The sample is then analyzed in the laboratory to determine whether or not there is a deficiency of megakaryocytes (platelet-producing cells) or an infiltrating disease.
Fibrinogen test: A small sample of blood is taken from the patient in order to measure the amount of fibrinogen (a coagulation factor) in the blood.
The risk of bleeding increases as the number of platelets decreases. When there are less than 10,000 platelets per microliter of circulating blood, the condition is considered severe, and internal bleeding may occur.
Hemorrhage: Hemorrhage is possible throughout the body. Intracranial (bleeding in the head) is another possible complication of thrombocytopenia.
Gastrointestinal bleeding: In serious cases, blood may be present in vomit or stools.
Stroke: Individuals suffering from thrombocytopenia are at an increased risk of stroke.